In digital systems the need frequently arises for one digital unit to communicate with another. The communication is usually accomplished most economically through interconnections employing wires or other conductors. Such interconnections, especially if they are lengthy and exposed, may be prone to failure under the influence of electrical, magnetic, or electromagnetic interference or surges; electromagnetic reflections from impedance discontinuities; or misconnection of wires to sources of damaging voltages or currents. The simplest and least expensive digital interconnections, such as 1-Wire and I2C (Inter-Integrated Circuit) find use in systems in which communications are required over short distances. Typically operating at voltages of 5 volts or lower, these digital interconnections are prone to interference. They typically interconnect chips or modules that are designed for low-voltage logic and that are easily damaged by excessive voltages. For longer-distance digital communications utilizing exposed cables and user-accessible or user-serviceable connectors more expensive interconnection schemes, such as Ethernet and TIA-485 (Telecommunications Industry Association standard number 485 also known as Recommended Standard number 485 or RS-485), which utilize differential signaling, are frequently preferred due to their reduced susceptibility to interference, and their higher voltages. The chips or modules that they interconnect are often hardened to withstand surges such as electrostatic discharges and ground fault events and to withstand high voltages that might be applied to the interconnect wires due to cable insulation failures or accidental misconnections. Chips that implement these hardened interconnections currently cost a few dollars apiece, and one such chip is required for each digital unit being interconnected. Operation of each such chip requires a certain amount of electrical power.